task_queue_impl.h | Explore in Territory

// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_TASK_SEQUENCE_MANAGER_TASK_QUEUE_IMPL_H_
#define BASE_TASK_SEQUENCE_MANAGER_TASK_QUEUE_IMPL_H_

#include <stddef.h>

#include <functional>
#include <memory>
#include <optional>
#include <queue>
#include <set>
#include <utility>
#include <vector>

#include "base/base_export.h"
#include "base/containers/flat_map.h"
#include "base/containers/intrusive_heap.h"
#include "base/dcheck_is_on.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/pending_task.h"
#include "base/task/common/checked_lock.h"
#include "base/task/common/operations_controller.h"
#include "base/task/sequence_manager/associated_thread_id.h"
#include "base/task/sequence_manager/atomic_flag_set.h"
#include "base/task/sequence_manager/enqueue_order.h"
#include "base/task/sequence_manager/fence.h"
#include "base/task/sequence_manager/lazily_deallocated_deque.h"
#include "base/task/sequence_manager/sequenced_task_source.h"
#include "base/task/sequence_manager/task_queue.h"
#include "base/task/sequence_manager/tasks.h"
#include "base/threading/thread_checker.h"
#include "base/time/time_override.h"
#include "base/trace_event/base_tracing_forward.h"
#include "base/values.h"

namespace base {
class LazyNow;
namespace sequence_manager::internal {

class SequenceManagerImpl;
class WorkQueue;
class WorkQueueSets;
class WakeUpQueue;

// TaskQueueImpl has four main queues:
//
// Immediate (non-delayed) tasks:
//    |immediate_incoming_queue| - PostTask enqueues tasks here.
//    |immediate_work_queue| - SequenceManager takes immediate tasks here.
//
// Delayed tasks
//    |delayed_incoming_queue| - PostDelayedTask enqueues tasks here.
//    |delayed_work_queue| - SequenceManager takes delayed tasks here.
//
// The |immediate_incoming_queue| can be accessed from any thread, the other
// queues are main-thread only. To reduce the overhead of locking,
// |immediate_work_queue| is swapped with |immediate_incoming_queue| when
// |immediate_work_queue| becomes empty.
//
// Delayed tasks are initially posted to |delayed_incoming_queue| and a wake-up
// is scheduled with the TimeDomain.  When the delay has elapsed, the TimeDomain
// calls UpdateDelayedWorkQueue and ready delayed tasks are moved into the
// |delayed_work_queue|. Note the EnqueueOrder (used for ordering) for a delayed
// task is not set until it's moved into the |delayed_work_queue|.
//
// TaskQueueImpl uses the WorkQueueSets and the TaskQueueSelector to implement
// prioritization. Task selection is done by the TaskQueueSelector and when a
// queue is selected, it round-robins between the |immediate_work_queue| and
// |delayed_work_queue|.  The reason for this is we want to make sure delayed
// tasks (normally the most common type) don't starve out immediate work.
class BASE_EXPORT TaskQueueImpl : public TaskQueue { … };

}  // namespace sequence_manager::internal
}  // namespace base

#endif  // BASE_TASK_SEQUENCE_MANAGER_TASK_QUEUE_IMPL_H_
chromium/base/task/sequence_manager/task_queue_impl.h
